Crystalline heat-resisting thermoplastic resins (these have a melting point of crystal of not less than 150.degree. C.) such as polyacetal, polyamide, aromatic polyester, poly(arylene sulfide), polyketones, poly(ether ketones), polyamideimide and poly(ether nitrile) are excellent in mechanical properties and moldability, and therefore are used for functional parts in the fields of automobiles, industrial machineries, office automation equipments, electrical and electronic equipments and the like. However there is a market demand for higher chemical resistance and sliding property and in addition, since these resins are generally brittle, enhancement in impact resistance is particularly desired. Also non-crystalline heat-resisting thermoplastic resins (these have a glass transition temperature of not less than 150.degree. C.) such as polycarbonate, poly(phenylene ether), polyarylate, polysulfone, poly(ether sulfone) and poly(ether imide) are widely employed for uses where their transparency, dimensional stability, impact resistance and the like are utilized, but generally have problems of chemical resistance, solvent resistance and moldability.
From another aspect, fluorine-containing resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene/hexafluoropropylene copolymer (FEP), poly(vinylidene fluoride) (PVDF) and ethylene/tetrafluoroethylene copolymer (ETFE) are excellent in thermal resistance, chemical resistance, solvent resistance, weather resistance, sliding property, flexibility, electrical properties and the like, and are widely used in the fields of automobiles, industrial machineries, office automation equipments, electrical and electronic equipments and the like. However as compared with the crystalline heat-resisting thermoplastic resins, in many cases, the fluorine-containing resins are inferior in mechanical properties and physical heat resistance as shown by a deflection temperature under load, and also are inferior in dimensional stability as compared with non-crystalline heat-resisting thermoplastic resins, and thus their application is limited.
In order to eliminate the drawbacks of the above-mentioned non-fluorine type heat-resisting thermoplastic resins, attempts for preparing novel materials have been aggressively made by combining with a fluorine-containing polymer (resinous and elastomeric ones are included) or, contrarily, by modifying the resinous fluorine-containing polymer with a non-crystalline heat-resisting thermoplastic resin.
First, as an example of simple melt-blending by means of a kneader, for instance, JP-A-202344/1982 discloses that a commercially available fluorine-containing elastomer is added to poly(arylene sulfide) for the purpose to improve impact resistance, crack resistance and strength against thermal shock without impairing the characteristics of poly(arylene sulfide) such as thermal resistance and chemical resistance. Also JP-A-165647/1989 and JP-A-110156/1990 disclose that a polymer forming an anisotropic melt, i.e. a liquid crystal polymer (aromatic polyester and the like) is added for the purpose to decrease a coefficient of linear expansion and further to improve mechanical properties and moldability without impairing weather resistance, chemical resistance, wear resistance and antisoil property of the fluorine-containing polymer such as PVDF. As examples of a blend of a liquid crystal polymer and PTFE, there are JP-B-5693/1992 and JP-A-230756/1988. JP-A-7850/1975 discloses that it is effective to blend PVDF for improving water absorption property and hygroscopicity of polyamide.
Further JP-A-23448/1985 discloses an example of improving mold-release property by incorporating a fluorine-containing polymer to an aromatic polysulfone composition of which shrinkage from mold dimensions is reduced by adding fibrous reinforcing agents such as glass fibers and wollastonite and inorganic fillers such as talc and glass beads.
Also attempts to improve sliding property by mixing PTFE powder to various synthesized resins have been widely conducted.
However there is a problem that usually the fluorine-containing polymer has poor affinity with other materials, because of a small surface energy thereof. For that reason, when the fluorine-containing polymer is melt-blended with other materials, there occurs a phase separation, and an interfacial adhesivity therebetween is substantially zero, and thus interfacial adhesion failure is easy to occur. In addition, the fluorine-containing polymer is difficult to disperse into other materials during blending, which results in aggregation and makes it difficult to sufficiently exhibit effects of adding the fluorine-containing polymer.
In order to resolve these drawbacks or enhance affinity between the different polymers, there is often added a compatibilizing agent as a third component. JP-A-218446/1987 discloses a composition prepared by blending a thermoplastic fluorine-containing elastomer in order to improve impact resistance of poly(arylene sulfide) without impairing its flowability, and teaches that it is more effective to add a polymer containing a fluorinated aliphatic group for improving the affinity. Also JP-A-62853/1991 discloses a method of adding, as a compatibilizing agent, a graft polymer comprising a vinyl polymer having epoxy group and methyl methacrylate polymer or acrylonitrile/styrene copolymer when blending poly(arylene sulfide) and a thermoplastic resin including PVDF.
Also claim 2 of the above-mentioned JP-A-165647/1989, JP-A-197551/1989 and JP-A-263144/1989 disclose that it is more effective to add an acrylic polymer, poly(vinyl acetate) and poly(vinyl methyl ketone), respectively to the blend of PVDF and an anisotropic melt-forming polymer as compared with simple blending.
In JP-A-11109/1989 there is described an example of using, as a compatibilizing agent for blending polyamide and PVDF, a block polymer comprising any one of N-vinylpyrrolidone or methyl (meth)acrylate and any one of an ethylenically unsaturated monomer, polycondensated monomer or lactum.
Also JP-A-98650/1989 and JP-A-110550/1989 disclose the use, as a compatibilizing agent when blending poly(phenylene ether) and a fluorine-containing polymer such as PVDF, of a copolymer comprising polystyrene and an acrylic polymer by utilizing excellent affinities of poly(phenylene ether) with polystyrene and of PVDF with an acrylic polymer.
However in JP-A-218446/1987, the effect of improvement in affinity is not enough because the fluorinated aliphatic group in the compatibilizing agent has a low degree of polymerization, i.e., not more than 20 of carbon atoms. Also all the other patent publications substantially direct to examples of using non-fluorine type compatibilizing agents synthesized by utilizing the excellent affinity between the PVDF and the carbonyl group-containing polymer such as an acrylic polymer, and thus the fluorine-containing polymer is limited to PVDF. Also in the affinity improving method using such compatibilizing agents, since chemical resistance and thermal resistance of the compatibilizing agents themselves are poorer than those of the main component polymer, there is a problem that physical properties of molded articles are lowered.
There are also attempts to improve dispersibility of compositions comprising fluorine-containing polymers and thermoplastic resins by so-called dynamic vulcanization. JP-A-185042/199 1 discloses that, when blending a crosslinkable fluorine-containing elastomer and a thermoplastic polymer having a melting point of crystal or glass transition temperature of not less than 150.degree. C., dispersibility of the fluorine-containing elastomer is improved to give a thermoplastic elastomer by conducting vulcanization of the fluorine-containing elastomer during melt-blending. Also in JP-A-172352/1991, fine dispersion of fluorine-containing rubbers has been achieved by utilizing the dynamic vulcanization method for improving impact resistance of poly(phenylene sulfide) with a fluorine-containing elastomer.
However in these dynamic vulcanization methods, since the fluorine-containing elastomer is vulcanized during melt-blending with other materials, impurities derived from a vulcanizing agent and other additives to be usually used for vulcanization remain in the composition, which makes the properties of molded articles such as chemical resistance lowered.
Also particularly because in a dynamically vulcanized composition comprising the thermoplastic resin and the fluorine-containing elastomer, the thermoplastic resin becomes a matrix, for example, chemical resistance of the composition is easy to be influenced by characteristics of the thermoplastic resin, and the effect of adding the fluorine-containing elastomer is not sufficiently obtained.
On the other hand, there are reports with respect to a composition comprising a fluorine-containing polymer with reactive functional group. JP-A-105062/1988, JP-A-254155/1988 and JP-A-264672/1988 disclose examples of a blend of a matrix polymer with a fluorine-containing polyether with functional group at its end(s), a polymer containing functional group and a polyfluoroalkyl group having 2 to 20 carbon atoms or a fluorine-containing elastomer with functional group. However, either of these examples is conducted in the way of letting two functional group-containing polymers disperse in the matrix polymer and react with each other to form a network structure, and then physically bond the network structure to the matrix polymer. Namely, the way does not directly utilize chemical affinity and reactivity with the matrix polymer.
Therefore a combination of two or more functional groups which react with each other is necessary, and it is required to regulate the conditions where those functional groups give a network structure. Also the fluorine-containing polyether is usually obtainable as an oily substance and is expensive, and moreover the effect of addition is limited to improvement of lubricity of the matrix polymer. Further as the polyfluoroalkyl-containing polymer, only ones having low molecular weight, which are difficult to be defined as polymer, are exemplified.
Also JP-A-112612/1993 discloses modified fluorohydrocarbon polymers to which substituents such as vinyl, allyl, acrylate, alkoxysilane, amide, sulfonic acid salt, pyridine and carboxylic acid salt are introduced. There is also described that among these substituents, particularly amide is further converted to amino and carboxylester being converted to carboxyl, and thus it is possible to graft to an aromatic polyamide and aromatic polyester. Also it is mentioned that the graft polymers are used for blending with commercially available engineering polymers to improve their surface characteristics, weather resistance, wear resistance and water absorption property.
However the substituents of these modified polymers are introduced by polymer reaction wherein Y-R-Z which is a combination of a highly reactive nucleophilic group Y (amino, oxy, thio) and the above-mentioned modifying substituent Z being connected through a bonding segment R, is reacted with a double bond formed in the vinylidene polymer by dehydrofluorination of the polymer.
That is, because of polymer reaction, it is difficult to introduce the substituents uniformly, and for that reason, there occurs an irregular distribution in the concentration of functional groups, and thus it is difficult to obtain sufficient effect on dispersibility and affinity at the time of blending with the thermoplastic resin.
Also at the time of introduction of the modifying substituents and hydrolysis of amide or carboxylester, there remains a reactive reagent, which results in lowering of thermal resistance and chemical resistance. Further since the bonding segment of the modifying reagent is of hydrocarbon type, thermal resistance of the obtained polymer itself is lowered at that portion and the polymer is decomposed when kneading with the heat-resisting thermoplastic resin at high temperature to lower the physical properties of the blended composition. Also the vinylidene polymer, after the dehydrofluorination, is colored markedly and external appearance of the molded article is impaired remarkably. Also in this method, the fluorine-containing polymer is limited to vinylidene fluoride polymers, and also introduction of hydroxyl group and glycidyl group is difficult, and thus sufficient effects of enhancing dispersibility cannot be obtained in blending with an aromatic polyester, polycarbonate and poly(phenylene sulfide). Further there is no detailed description as to examples of the composition blended with the heat-resisting thermoplastic resin and the physical properties at the time of blending.
JP-A-8 1159/1988 discloses that mechanical properties of a thermoplastic elastomer composition can be improved by modifying a fluorine-containing rubber with any one of carboxyl, hydroxyl or epoxy group when blending a poly(ether ester amide) and the fluorine-containing rubber.
However the described fluorine-containing rubber with functional group is prepared by copolymerizing a fluorine-containing monomer and an acrylic monomer with functional group to introduce the functional group. Therefore, the thermal resistance and chemical resistance are lowered and physical properties of a molded article is lowered when blended with the heat-resisting thermoplastic resin. The functional group-containing acrylic monomer has poor copolymerizability with a fluorine-containing monomer represented by tetrafluoroethylene and vinylidene fluoride, and a uniform concentration of functional groups is difficult to obtain in every polymer molecule, which results in an irregular distribution of components. Thus it is difficult to obtain sufficient effects on dispersibility and affinity in blending with the thermoplastic resin. Also poly(ether ester amide) is usually low in chemical resistance as compared with polyamide.
As mentioned above, when blending a fluorine-containing polymer and a thermoplastic resin, since the fluorine-containing polymer usually has poor affinity, it is difficult to obtain a blend having stable characteristics, and physical properties of the molded article obtained therefrom is lowered. Also though various attempts have been made for improving the affinity, such as study on additives and modification and denaturation of the fluorine-containing resin, there have not been obtained a fluorine-containing polymer and a composition prepared by mixing the fluorine-containing polymer and a thermoplastic resin, which do not lower thermal resistance and chemical resistance of the composition.